Self-normaling jack barrel assembly with impedance balancing element



D 26, 96 J. F. LANCASTER 3,

SELF-*NORMAL'ING JACK BARREL ASSEMBLY WITH IMPEDANCE BALANCING ELEMENT Filed July 19, 1965 5 Sheets-Sheet l +13 v INVENTOR JESSE LANCASTER BY MVMWM 7! A ORNEY5 Dec. 26, 1967 Y J. F. LANCASTER 3,360,747

SELFNORMALING JACK BARREL ASSEMBLY WITH IMPEDANCE BALANCING ELEMENT Filed July 19, 1965 5 Sheets-Sheet 2 INVENTOR JESSE E LANCASTER BY ,WWM Q ATTQRNEYS Dec. 26, 1967 J. F. LANCZASTER 3,

SELF-NORMALING JACK BARREL ASSEMBLY WITH IMPEDANCE BALANCING ELEMENT Filed July 19, 1965 5 Sheets-Sheet 3 $27.5 55 v K 53 7 i INVENTOR 59 64 555 E LANCASTER ATTORNEYS Dec. 26, 1967 J. F. LANCASTER SELF-NORMALING JACK BARREL ASSEMBLY WITH IMPEDANCE BALANCING ELEMENT 5 Sheets-Sheet 4 Filed July 19, 1965 INVENTOR JESSE F LANCASTER BY gima myzm 774w Mfiwma l ATTORNEYS Dec. 26, 1967 J. F. LANCASTER v 3,360,747

SELF-NORMALING JACK BARREL ASSEMBLY WITH IMPEDANCE BALANCING ELEMENT Filed July 19, 1965 5 Sheets-Sheet 5 I I T:

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INVENTOR asssz E LANCASTER Z7 ,Z4 349 34a BY Mimi/m 347 345a 346 aw ME ATTOR NEYS United States Patent Ofifice 3,360,747 Patented Dec. 26, 1967 SELF-NORMALING JACK BARREL ASSEMBLY WITH IMPEDANCE BALANCING ELEMENT Jesse F. Lancaster, Great Falls, Va., assignor to Cooke Engineering Company, Alexandria, Va., a corporation of Delaware Filed July 19, 1965, Ser. No. 472,977 Claims. (Cl. 333-9) This invention relates to jacks for connecting coaxial cables together or for selectively disconnecting them and connecting them to other cables. In particular, the invention relates to a self-normalling jack which in its normal condition connects a coaxial cable from video or other radio frequency energy source to a similar cable leading to a load, but wherein patchcords may be inserted into the jack to connect the energy source to a difierent load or to connect the load to a different source.

Jacks of this type have internal switching devices for disconnecting the normally connected source and load upon the insertion of a patchcord or dummy plug. They usually comprise a pair of jack barrels rigidly mounted in parallel upon a plate and a number of the jacks are mounted on a panel to provide a jackfield so that patchcords may be inserted into selected jacks to connect different circuits together as needed. The jacks may include resistors and other devices that match the characteristic impedance of a circuit connected to it, so that the cable leading thereto may be properly terminated when the circuit is disconnected at the jack.

Jacks of the type to which the invention pertains are exemplified by the Patents 2,958,054 issued Oct. 25, 1960 to Concelman; 3,020,365 issued Feb. 6, 1962 to Neenan; 3,109,997 issued Nov. 5, 1963 to Giger et all; 3,117,193 issued Jan. 7, 1964 to Hirshfeld et al. and 3,036,169 issued May 22, 1962 to Kienlen et a1.

All of the illustrated embodiments of the invention are of simplified rugged construction, leading to low cost, long life, ready assembly, permitting miniaturization and providing low cross talk and noise pickup.

Several embodiments are improved and refined versions of the jack shown in the aforementioned Patent 3,036,169 issued May 22, 1962 to Kienlen et 211.

All provide resistor means for matching and terminating a disconnected cable with an impedance matching the circuit to which the disconnected cable leads.

It is accordingly a primary purpose of the invention to provide an improved self normalling jack for connecting or disconnecting coaxial cables or for connecting them to other cables.

Another important object is to provide a self normalling jack having features of construction that permit miniaturization and yet lead to a rugged device that is readily assembled.

Still another important object of the invention is the provision of improved and novel means for terminating a disconnected coaxial cable 'by connecting its inner and outer conductors through a resistor balanced for the characteristic impedance of the circuit to which the cable leads.

Other objects will become apparent as the description FIGURE 4 is a view in side elevation, partly in section of an insulator block assembly used in the embodiment of FIGURES 1 to 3.

FIGURE 5 is a top plan view of the assembly of FIG- URE 4.

FIGURE 6 is a side view of the assembly of FIGURE 4, as seen from the right of FIGURE 4.

FIGURE 7 is a top plan view of a second embodiment of a self terminating unit with a portion of the cover removed to expose the switch parts.

FIGURE 8 is a vertical sectional view substantially along the line 8-8 of FIGURE 7, but with some parts omitted.

FIGURE 9 is a bottom view of the unit of FIGURE 7, with a portion of the cover removed to expose the switch parts.

FIGURES 10 and 11 are top plan and bottom views respectively of a third embodiment, with portions of the cover removed in each case to expose the switch parts.

FIGURES 12 and 13 are top plan and bottom views respectively of a fourth embodiment, with portions of the cover removed in each case to expose the switch parts.

FIGURE 14 is an enlarged side view of a portion only of the shorting rod and associated contacts, as viewed substantially from the line 14-14 of FIGURE 12.

FIGURE 15 is a horizontal sectional view taken substantially through the center of a fifth embodiment of the invention.

Referring to FIGURES 1 to 3, wherein is shown one form of a normal-through coaxial switching and line terminating jack, a pair of tubular metal jack barrels or shields 18 and 19 extend through and are rigidly secured to a common metallic bar 28. Within jack barrel 18 is a conductor 21 fixedly mounted centrally therein by an insulator 22 and within jack barrel 19 is a similar central conductor 23 fixedly mounted therein by an insulator 25. A transverse conductor or shorting rod 24, in its normal position, connects the central conductors 21 and 23. Thus if two coaxial cables are connected to the jack by connectors, not shown, by inserting them into the right ends of jack barrels 18 and 19 the two coaxial cables are connected together by the normal-through jack shown, when the transverse conductor or shorting rod 24 is in its normal position engaging 'b-oth central conductors 21 and 23. The outer conductors of the cables are connected via barrels 18 and 19 and bar 20. The coaxial cable connected to jack barrel 18 may lead from a video or other radio frequency source, in which case the coaxial cable connected to the other jack barrel 19 will lead to a corresponding load. The construction by which the coaxial cables connected to the right ends of barrels 18 and 19 may be either terminated at the jack or else connected to another source or load will now be described.

A pair of spaced ears 26 and 27, are affixed to the bar 20 as by soldering or brazing and are transversely drilled to receive a hinge pin 28 which has a sliding fit therein, the hinge pin being above the barrels 18 and 19 as viewed in FIGURES 2 and 3. A pair of shorting rod levers 30 and 31 of insulating material, which are similar but reversed in plan outline as viewed in FIGURE 1, are pivotally mounted upon the hinge pin 28 and their outer free ends are resiliently urged clockwise, as viewed in FIG- URE 2, toward the central conductors 21 and 23, by springs 32 and 33 having their coils mounted on hinge pin 28. The spring 32 has a protruding leg 36 received in a groove in the edge of bar 20 and a substantially oppositely protruding leg 37 received in a groove in the upper surface of the shorting rod lever 30, and the spring is so tensioned as to urge the lever 30 toward the conductor 21 as previously mentioned. Spring 33 is similarly tensioned and has protruding legs 38 and 39 similarly received in slots in bar 20 and the other lever 31.

The upper portions of the jack barrels 18 and 19, as viewed in FIGURE 2, are cut away as indicated at 40 in FIGURE 2 and at 40 and 41 in FIGURE 1, to provide access to the interior of the barrels by the shorting rod levers 30 and 31 to move the shorting rod 24 toward and away from the central conductors 21 and 23, and also to provide room for movement of the shorting rod itself since it extends between and overlies the central conductors within the barrels.

Adjacent its free end the lever 31 has a bore 44, which as best shown in FIGURE 2 is about twice the diameter of the shorting rod 24, which passes therethrough with a very loose fit. The other lever 30 has a similar large bore 45 for the passage of the rod 24. A pair of spaced shoulders 46 and 47 (FIGURE 1) on the shorting rod 24 are larger in diameter than the aforesaid bores 44 and 45 and axially spaced so as to permit substantial axial movement of rod 24 but to prevent its withdrawal from either bore 44 and 45 during operation of the jack. The bores 44 and 45 are in relatively narrow extending leg portions 48 and 49 on the free ends of the shorting rod levers 30 and 31 respectively, which portions extend downwardly and between the central conductors 21 and 23 so that the shorting rod 24 can engage the central conductors when in the normal position, as best seen in FIGURE 2.

Also pivotally mounted upon the hinge pin 28 is a block of insulating material designated generally by the reference numeral 51 in FIGURES 3 to 6. The block 51 comprises a substantially rectangular base 52 and a pair of spaced upstanding legs 53 and 54 having aligned bores 55 and 56 therethrough by which the block is mounted upon the pin 28. A ground contact leaf spring 59 is secured to the top of base 52 as by a rivet 60 and has a leg 61 depending below the base to which is soldered one lead of a balancing resistor 62. A resistor contact leaf spring 63 has a free end extending between the base 52 and the free end of ground contact spring 59, overlying the shorting rod 24. It is secured to the top of base 52 by a rivet 64 and has a leg 65 depending below the base and to which is soldered the other leg of the resistor 62.

Clockwise rotation of the insulator base 52 beyond a substantially horizontal position as viewed in FIGURES 2 and 4 is prevented by engagement of its left end 66 with the metal bar 20. It is resiliently held in this position by the shorting bar 24 when the shorting bar is engaging both central conductors 21 and 23, and in this position the shorting bar is spaced below and does not engage the resistor contact leaf spring 63, as best shown in FIG- URES 2 and 4.

A metallic box-like shielding enclosure 67 encloses all of the movable parts of the switch. It has a tight fit over the metallic bar which forms one wall of the enclosure. Slots 74 (FIGURE 2) adjoining the openings for the barrels 18 and 19 permit the enclosure to slip over the prongs 75 on the barrels which are engageable by conventional coaxial cable BNC connectors. Ring grooves 76 are also provided so that connectors disclosed in the copending application Ser. Number 471,105 filed July 12, 1965, now Patent No. 3,325,767 by Jesse F. Lancaster for Connector may be used on the coaxial cables.

The jack has so far been described in its normal condition, with the two coaxial cables (not shown) attached to the right hand ends of jack barrels 18 and 19 connected to each other by engagement of the shorting rod with both central conductors 21 and 23.

The circuit can be broken by inserting a dummy plug into the left end of either jack barrel 18 or 19 or by inserting a patchcord into either jack barrel. Patchcords may be inserted into both barrels at their left ends, but the connection between central conductors 21 and 23 will be broken upon insertion of the first one, as will be apparent from the following description.

FIGURE 2 shows the end of a patchcord 68 partially inserted into the left end of jack barrel 19. The patchcord includes an outer metal tube 69 which has a sliding fit within the jack barrel, a central conductor 70, and a tubular insulator 71 separating the central conductor from the metal tube 69. At its right end the insulator has a counter-bore 72 to receive the reduced diameter left end of insulator 25. Central conductor 70 extends to the left end of counter-bore 72, and surrounding the right end portion of the central conductor 70 is a second small counter-bore 73 so that when the patchcord 68 is fully inserted into jack barrel 19 there will be room for the prongs of the fixed central conductor 23, which surround and engage the end of conductor 70 when the patchcord is fully inserted.

Referring still to FIGURE 2, as the patchcord 68 is inserted, continued movement to the right from the position shown will result in engagement of the leading edge of the metallic tube 69 with a carnming surface on the bottom face of the shorting rod lever 31, turning the lever counterclockwise about the hinge pin 28. Further movement of the patchcord to the right, into full engagement with the contact 23 results in rotating the lever to its fully raised position, in which it is substantially horizontal with a fiat portion 81 on its bottom surface engaging the top of the tube 69 of the patchcord. The bore 44 in the outer end of the lever is then in the position shown in dot dash lines at 44a and the end of the shorting rod 24 passing therethrough is in the position shown at 24a. The other end of the shorting rod 24 is still engaged against the other central contact 21, being retained thereagainst by the spring 32 and shorting rod lever for the other jack barrel 18, and the shorting rod is in the inclined position shown at 24a in FIGURE 3. The loose fit of the shorting rod in the bores 44 and 45 in the levers permits this. In its movement to this inclined position the mid-portion of the shorting rod engages the underside of the resistor leaf spring and raises it to the position 63:: in FIGURES 2 and 3. This rotates the insulator block 51 counterclockwise and raises the ground contact leaf spring 59 to the position shown at 59a in FIGURES 2 and 3, in which position the spring 59 contacts the metallic shielding enclosure 67, thus grounding the central conductor 21 in jack barrel 18 by way of shorting rod 24, resistor contact leaf spring 63, resistor 62 and the ground contact spring 59. The latter becomes stressed upon engagement with enclosure 67 and resiliently urges the insulator block 51 clockwise so that the resistor contact leaf spring will maintain firm contact with the central portion of the shorting rod.

In this condition the patchcord 68 in jack barrel 19 is now fully connected to the coaxial cable connected to the right hand end of the jack barrel and leading to a load, and the cut away opening 40 in the upper portion of the jack barrel is fully covered by the metal tube 69 of the patchcord. Also, the coaxial cable connected to the right hand end of the other jack barrel 18 is terminated, being grounded through the resistor 62 to the enclosure 67. The value of the resistor 62 is selected in accordance with the impedance of the circuit connected to the right ends of the jack barrels. Normally a video or other radio frequency source is connected to barrel 18 and a load to barrel 19.

With the patchcord 68 leading to an alternate video or other radio frequency source fully inserted into the jack barrel 19 the load connected to the right end of the jack barrel is now supplied by the alternate source, Withdrawal of the patchcord 68 will lower the shorting rod 24 and reestablish the connection between the central connectors 21 and 23. Lowering of the shorting rod will also lower the insulator block 51, disengaging spring 59 from the enclosure 67 and spring 63 from the shorting rod.

If it is desired to connect the energy source connected to the right end of jack barrel 18 to another load, then a patchcord 82, similar to patchcord 68, but leading to the other load may be inserted into the left end of jack barrel 18. This will raise the right end of shorting rod 24 as viewed in FIGURE 3, disengaging it from the central conductor. If at this time there is already a patchcord inserted in the other jack barrel 19 then the shorting rod 24 will be level, with both ends raised to the same level as the left end of the dot-dash view of the rod at 24a in FIG- URE 3. This will raise the resistor contact leaf spring 63 to a position higher than indicated at 63a, against the force of ground contact leaf spring 59 which will remain at position 59a, in engagement with the enclosure 67. If the patchcord should now be removed from the jack barrel 19 the right end of shorting rod 24 as viewed in FIG- URE 3 will remain elevated and its left end will be lowered into engagement with the central conductor 23, grounding it via contact leaf spring 63, resistor 62 and spring 59 to the enclosure 67.

Assuming, as before, that central conductor 21 in jack barrel 18 is connected to a video or other radio frequency source, and that central conductor 23 in jack barrel 19 is connected to a receiver as a load, the grounding of the receiver central conductor 23 via the balancing resistor 62 upon disconnection from the source central conductor 21 will prevent the receiver from going into oscillation and affecting other circuits.

If it is only desired to disconnect central conductor 21 from central conductor 23 rather than perform a switching operation by the insertion of patchcords as described above, a dummy plug inserted into either jack barrel will perform the disconnection by raising the corresponding end of the shorting rod away from the central contact. If central contact 23 is connected to a receiver it is preferable to insert the dummy plug into the jack barrel 18 so that the central contact 23 is grounded, preventing possible oscillation of the receiver. The dummy plug may be similar to a patchcord plug, omitting the central conductor therein.

In the embodiment illustrated in FIGURES 7, 8 and 9 a pair of jack barrels 118 and 119 are rigidly secured to a common metallic bar 120, the jack barrels have central insulated conductors 121 and 123 and a shorting rod 124 is loosely mounted in bores in the outer ends of shorting rod levers 130 and 131 of insulating material, hinged on pin 128, which resiliently hold the shorting rod against the central conductors 121 and 123 under the action of springs 132 and 133, all as in the first embodiment. A block 129 of insulating material, shown in section in FIGURE 8, has a pair of spaced upwardly extending legs 126 and 127 in which is mounted a hinge pin 128 that supports the levers 130 and 131 and their springs 132 and 133. The block 129 is rigidly secured to the metal bar 120 as by screws, not shown.

Mid-point of the length of block 129, mid-point between the jack barrels 118 and 119, a resistor contact leaf spring 163 is mounted, being secured thereto by a hollow rivet 164 through a leg 165 of the spring 163 that extends beneath the block 129. The latter has a vertical passageway 157 therethrough, in which is located a balancing resistor 162 one lead of which is soldered to the leg 165, the other lead being soldered to a ground contact leaf spring 159 which is secured to the underside of block 129 by a hollow rivet 160.

As shown in FIGURE 9 the ground contact leaf spring 159 extends away from the rivet 160 on opposite sides thereof and terminates in two legs 183 and 184 underlying the jack barrels 118 and 119 respectively and extending to the right ends thereof to which coaxial cables are connected. Near their right ends the legs 183 and 184 of the spring 159 have upwardly deformed portions forming contacts 185 and 186 which protrude through openings 187 and 188 through the bottom walls of jack barrels 118 and 119. The contact 185 is best shown in FIGURE 8. Both contacts 185 and 186 protrude through these openings so as to lie in the path of the external metal tubes of either patchcords or dummy plugs inserted into the left ends of jack barrels 118 or 119. Thus when a patchcord or dummy plug is fully inserted, the left lead of the balancing resistor is grounded by Way of ground contact spring 159, leg 183 or 184, con- 6 tact 185 or 186, jack barrel 118 or 119, and metallic bar 120. As will be understood, the contacts 185 and 186 do not engage any portion of the jack barrels 118 or 119 at any time.

In the normal condition of the switch of this embodiment the shorting rod 124 engages the central conductors 121 and 123. It has a loose fit in the free ends of the shorting rod levers and 131 and has an enlarged central portion 146 to keep it from slipping axially out of the levers. In this condition the enlarged portion 146 of the shorting rod is substantially in the position shown in FIGURE 8. Upon full insertion of a patchcord or dummy plug into either jack barrel one end of the shorting rod will be raised out of engagement with its central conductor, and the mid-point of its enlarged portion will be at the position 146a of FIGURE 8, where it has engaged and raised the free end of the resistor contact leaf spring 163 to the position indicated at 163a. This grounds the central conductor in the other jack barrel through the shorting rod, spring 163, resistor 162, ground contact spring 164 and the external metallic tube on the inserted patchcord or plug. Inserting a patchcord into the other jack barrel will raise the other end of the shorting rod 124 from engagement with its central conductor so that both ends will be elevated and its enlarged central portion 146 will be higher than the position indicated at 146a in FIGURE 8, but still in engagement with the spring 163.

As in the case of the first embodiment, the upper portions of the jack barrels are cut away at and 141 to provide access for the shorting rod and its levers 130 and 131, these openings being closed when a patchcord or dummy plug is inserted into a jack barrel. A metallic shielding enclosure 167 encloses the mechanism, it being cut away at 168 in FIGURE 9 to expose the internal parts.

The embodiment of FIGURES 10 and 11 is similar in many respects to that of FIGURES 7, 8 and 9. Its jack barrels 218 and 219 have cut away portions 240 and 241 to provide access to the interiors thereof and to permit movement of a shorting rod 224 and its shorting rod levers 230 and 231 toward and away from the central conductors 221 and 223 therein. A mounting block 229 of insulating material is secured to a metal bar 220 to which are rigidly secured the jack barrels 218 and 219. Block 229 includes a pair of spaced legs 226 and 227 through which passes the hinge pin 228 for the levers 230 and 231 and which also supports the torsion springs 232 and 233. A resistor contact leaf spring 262 having a pair of spaced parallel legs 263 and 265 and a short central leg 264 is secured in a substantaially horizontal plane to an upper face on block 229 as by a screw 257. Neither of the spring legs 263 or 265 contact the shorting rod when it is in its lowermost position and in engagement with central contacts 221 and 223. On the underside of the block 229 a substantially U-shaped ground contact spring 259 is secured as by a screw 260 and has contacts 285 and 286 at the ends of its legs which protrude upwardly through openings 287 and 288 in jack barrels 218 and 219 respectively and into the pathway of the metallic tubes on patchcords or dummy plugs inserted into the left ends of the jack barrels. A balancing resistor, not shown, is mounted within the insulating block 229. One lead thereof is soldered to the central leg 264 of the resistor contact spring 262 at 269 and the other lead is soldered at 270 to an integral projecting lug 271 on the ground contact spring 259. In order to prevent grounding between the resistor contact spring 262 and the hinge pin 228 which are in close proximity, that portion of the hinge pin between the levers 230 and 231 is covered with a tube 272 of insulating material.

Upon full insertion of a patchcord or dummy plug into the left end of jack barrel 218 the corresponding end of the shorting rod 224 will be raised away from 7 the central conductor 221 and into contact with leg 263 on the resistor contact spring 262. This will ground the central conductor 223 in the other jack barrel 219 via the shorting rod 224, leg 263 and spring 262, the resistor, ground contact spring 259, contact 285, and the metallic tube on the patchcord in the jack barrel 18. The insertion of a patchcord in only the other jack barrel 219 will ground the central conductor 221 in the jack barrel 218 via the shorting rod, leg 265 on the resistor contact spring 262, the resistor, ground contact spring 259,

contact 286 and the metallic tube on the patchcord in the jack barrel 18.

The presence of patchcords fully inserted into both jack barrels will raise the shorting rod out of engagement with both central conductors 221 and 223, and the closure of both cut away openings 240 and 241.

A metallic shielding enclosure 267 has openings 290 and 291 therethrough in FIGURES l and 11 to expose the internal parts to view for purposes of illustration.

The embodiment of FIGURES 12, 13 and 14 is similar in operation to the previously described embodiments except for the manner in which the patched out line is grounded and so only this mechanism will be described in detailplack barrels 318 and 319, metal bar 320, central conductors 321 and 323, shorting rod levers 330 and 331 and their torsion springs 332 and 333, and hinge pin 328 are similar to those in the previously described embodiments. Insulating block 329 has two upwardly extending outer legs 326 and 327 and two spaced inner legs 334 and 335, the hinge pin 328 passing through all four legs.

A shorting rod indicated generally at 324 is shown to enlarged scale in FIGURE 14. This shorting rod differs from those previously described in that it includes a balancing resistor 338 which is mounted within two similar metallic cups 339 and 340 that have their open ends facing each other and separated by a gap through which is visible the central portion of the insulating covering of the cylindrical shaped resistor 338. The two leads of the resistor are soldered to the cups 339 and 348 respectively, and the resistor is secured within the cups by a suitable cement to provide a rigid assembly. The shorting rod 324 is completed by oppositely extending coaxial metallic pins 341 and 342 which are preferably integral with the cups 339 and 340 to provide sufficient strength. It is loosely mounted in holes through the free end portions of the shorting rod levers 330 and 331 as in the previously described embodiments.

Mounted in a recess 343 on the underside of insulating block 329 by a screw 344 is a resistor shorting leaf spring 345 which is bifurcated to provide a pair of parallel legs 346 and 347 that extend to the right as viewed in FIG- URE 13, to a point where they underlie the shorting rod 324. Their outer ends are turned upwardly to provide contacts 348 and 349 which resiliently engage the bottom side of the metallic cups 339 and 340 when the shorting rod is in engagement with both central conductors 321 and 323 as shown in the full lines in FIGURE 14. This is the condition of the jack when in its normal condition, without a patchcord or dummy plug inserted into the left end of either jack barrel 318 and 319. Central conductor 321 is connected to central conductor 323 via the shorting rod 324 and the resistor shorting leaf spring 345 which shorts out the resistor 338.

Mounted upon an upper surface of the insulating block 329 is a ground contact leaf spring 359 shown in FIG- URE 12. It extends between the inner legs 334 and 335 of the insulating block and is held in place by the hinge pin 328 and by a metal lug 360 which is soldered or otherwise secured to the metal bar 320. Thus it is electrically connected to bar 320 by the lug 360 as well as by the hinge pin 328 and the coil springs 332 and 333. The righthand portion of the spring 359 is bifurcated to provide legs361 and 362 which overlie, but do not engage the metal cups 339 and 348 of the shorting rod 324 when the 8 jack is in the normal condition as shown in full lines in FIGURE 14.

Now if a patchcord is inserted into the left end of jack barrel 318 it will raise the pin 341 (FIGURE 14) of the shorting rod to the position shown in dot-dash lines at 341a. The other pin 342 will remain in engagement with central conductor 323 which will now be grounded by way of pin 342, cup 340, resistor 338, cup 339, leg 361 v of spring 359 and lug 360 (as well as hinge pin 328 and the torsion springs 332 and 333). It will be noted from FIGURE 14 that in this condition the spring leg 361 has been raised to the position 361a but that spring leg 362 remains undisturbed, and is not engaged by the metal cup 340 because if it were the resistor 338 would be by-passed. Also, the metal cups 339 and 340 are raised to a position out of engagement with the legs on the resistor shorting spring 345, the outer free end of which has risen substantially to the position shown in dot-dash lines at 345a.

As will be understood, if the patchcord had been inserted into the other jack barrel 319 the shorting rod 324 would be tilted in the reverse direction in FIGURE 14, and if patchcords are in place in both jack barrels then both sides of the shorting rod will be elevated and both sides of the resistor will be grounded.

In the embodiment of FIGURE 15 instead of a shorting rod as used in the previously described embodiments, a substantially V shaped shorting leaf spring indicated gen erally at 424 is used.

Jack barrels 418 and 419 are rigidly secured to a common metallic bar 420 and have central conductors 421 and 423 mounted therein centrally of insulators 422 and 425. Coaxial cables leading to a video or other radio frequency source and to a load are secured to the left ends of jack barrels 418 and 419 respectively, and the right ends are adapted for the insertion of patchcords or dummy plugs as in the previous embodiments. A metallic shielding enclosure 467 encloses the internal mechanism of the jack and has a tight fit over the bar 420 to hold it in place.

A block 429 of insulating material is mounted between the two jack barrels, being secured to bar 420 as by screws, not shown. The block has end portions 430 and 431 which are cut by the plane of the sectional view, and a recess 432 lying behind that plane. The V shaped spring 424 lies within this recess, against its planar surface, which is smooth so as to eliminate friction between the surface and the spring during movement of the latter. The right end of the spring 424 is formed into a partial circular loop 433 which fits within a mating semicircular recess 437 having a surface 438 coplanar with the surface of recess 432. In the position shown in FIGURE 15 the leg 439 and 440 of the shorting spring 424 are compressed toward each other from their unstressed positions, and their outer ends are in resilient engagement with the central conductors 421 and 423 respectively, thus electrically connecting the central conductors. An insulating pin 441 of nylon or the like, within the recess 437 limits sliding movement to the left of the spring loop 433 within the recess.

In order to increase the force of the resilient contact between the outer ends 439 and 444 of the shorting spring 424 against the central conductors 421 and 423 a helper leaf spring 444 may be used. This spring is slightly wider than the shorting spring, and is seated within a recess 445 that is slightly deeper than the recess 432. Spring 444 has legs 446 and 447 that bear against the inner surfaces of legs 439 and 446 of the shorting spring 424. At its left end the helped spring has a partially circular loop 448 which surrounds a pin 449 of nylon or the like that prevents movement of the helper spring to the right.

Protruding above the surface of the recess 432 in the insulating block 429 and into the plane of the shorting spring 424 is an elongated metallic contact block 453 which has a portion 454 that extends through the insulating block to the other side thereof where it is soldered to one lead of a balancing resistor 455, the other lead of which is grounded to the metallic bar 420 as indicated at 456.

Jack barrels 418 and 419 are cut away to provide openings 458 and 459 that face each other and permit the legs 439 and 440 of the shorting spring to enter the barrels and engage the central conductors 421 and 423. A pair of actuating levers 461 and 462 of insulating material also have their free ends protruding through the openings 458 and 459, their other ends being hinged upon pins 463 and 464.

The normal condition of the jack is as shown in FIG- URE 15, with the central conductors 421 and 423 connected by the shorting leaf spring 424. If now a patchcord is inserted into the right end of jack barrel 418 its metal outer tube will engage and turn the actuating lever 461 counterclockwise to its depressed position shown at 461a. When in this position the lever 461 has disengaged the leg 439 of the shorting spring from the central conductor 421 and forced it into resilient engagement with one end of the metallic contact block 453. The leg 439 becomes slightly bowed when in this position, as shown in the dot-dash position at 439a, since the lever 461 engages the leg substantially at its mid-length.

In this condition a new load is connected to the jack barrel 418 and its central conductor 421. The load connected to the left end of jack barrel 419 is now grounded, the central connector 423 being grounded via shorting spring leg 440, loop 433, leg 439, contact block 453 and resistor 455. As in the other embodiments a patchcord may also be inserted into the right end of the other jack barrel 419, and if there is no patchcord in jack barrel 418 its central conductor will be grounded when the leg 440 of the shorting spring is engaged with the lower end of contact block 453. Patchoords may be inserted into both jack barrels at the same time, in which case both of the legs 439 and 440 will be disengaged from their central conductors and will engage the opposite ends of the contact block 453.

All of the illustrated embodiments of the invention are of simple rugged construction, leading to long life, ready assembly, and facilitating miniaturization.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. A self-normalling jack for selectively connecting a first coaxial cable to a second, or for disconnecting them, and also adapted to connect either of them to other coaxial cables when disconnected from each other, comprising,

(a) first and second jack barrels rigidly and electrically connected together, each having adjacent one end thereof a central conductor insulated from the barrel, but with exposed uninsulated portions within the barrel, the other ends of said jack barrels being open and the wall of each jack barrel having a transverse opening therethrough aligned with the exposed portion of said central conductors,

(b) a shorting rod extending transversely of said jack barrels, into said transverse openings therethrough and with its opposite ends engaging the exposed portions of said central conductors, thereby connecting them,

(c) resilient means urging said shorting rod into engagement with said central conductors,

(d) non-conductive means extending into said transverse opening in said jack barrels and into the path of a patchcord or dummy plug inserted into the open end of either barrel,

(e) said non-conductive means each being effective to separate one end of said shorting rod from its respective central conductor upon the insertion of a patchcord or dummy plug into the open end of its respective jack barrel,

(f) a normally electrically floating circuit impedance balancing element,

(g) and means operative to electrically connect said circuit impedance balancing element to said shorting rod and to said jack barrels upon separation of either end of said shorting rod from its respective central conductor.

2. In the jack described in claim 1, said last named means comprising,

(a) a first contact engageable and moveable by said shorting rod in its separating movement away from either of said central conductors and a second contact operable by said first contact in its movement to make an electrical connection to said jack barrels,

(b) said circuit impedance balancing element being connected to said first and second contacts.

3. In the jack described in claim 1,

(a) a hinge pin fixed with respect to said jack barrels,

(b) said non-conductive means being rotatably mounted upon said hinge pin,

(c) and said last named means comprising first and second contacts rotatably mounted upon said hinge pin for movement as a unit.

4. In the jack described in claim 1,

(a) a hinge pin fixed with respect to said jack barrels,

(b) said non-conductive means being rotatably mounted upon said hinge pin,

(c) said last named means comprising first and second contacts rotatably mounted upon said hinge pins as a unit,

(d) and said impedance balancing element being connected with said first and second contacts and mounted for movement therewith.

5. In the jack described in claim 1,

(a) a hinge pin fixed with respect to said jack barrels,

(b) said non-conductive means being rotatably mounted upon said hinge pin,

(c) an insulator block rotatably mounted upon said hinge pin,

(d) said last named means comprising a first contact engageable by said shorting rod in the movement of either end thereof away from its respective central conductor, and operable to rotate said insulator block,

(e) said last named means also including a second contact operable to connect electrically to said jack barrels upon rotation of said insulator block by said first contact,

(f) and said circuit impedance balancing element being mounted upon said insulator block and connected between said first and second contacts.

6. The jack described in claim 1, wherein,

(a) said last named means comprises a first contact engageable by said shorting rod in its separating movement away from either of said central conductors and a pair of electrically connected second contacts each protruding into one of said jack barrels into the path of the external metal tube on a patchcord or dummy plug inserted into either barrel,

(b) and said circuit impedance balancing element being connected between said first and second contacts.

7. -In the jack described in claim 6, said shorting rod comprising a pair of spaced metallic cups with their open ends facing each other, a resistor fixedly seated within and electrically connected to said cups, and coaxial conductive pins protruding outwardly from the closed ends of said cups.

8. The jack described in claim 6, wherein,

(a) each jack barrel has a second opening through the wall thereof,

(b) and said second contacts protrude through said second openings into said jack barrels.

9. The jack described in claim 1 wherein said circuit impedance balancing element is a resistor.

10. A self-normalling jack for selectively connecting a first coaxial cable to a second, or for disconnecting them, and also adapted to connect either of them to other coaxial cables when disconnected from each other, comprising,

(a) first and second jack barrels rigidly and electrically connected together, each having adjacent one end thereof a central conductor insulated from the barrel, but with exposed uninsulated portions within the barrel, the other ends of said jack barrels being open and the wall of each jack barrel having a transverse opening therethrough aligned with the exposed portion of said central conductors,

(b) a shorting rod extending transversely of said jack barrels, into said transverse openings therethrough and with its opposite ends engaging the exposed portions of said central conductors, thereby connecting them,

(0) resilient means urging said shorting rod into engagement with said central conductors,

(d) non-conductive means extending into said transverse openings in said jack barrels and into the path 12 of a patchcord or dummy plug inserted into the open end of either barrel,

(e) said non-conductive means each being eifective to separate one end of said shorting rod from its respective central conductor upon the insertion of a patchcord or dummy plug into the open end of its respective jack barrel,

(f) said shorting rod comprising an assembly of a pair of conductors and a circuit impedance balancing resistor, said conductors being separated by and connected to the leads of said resistor,

(g) a resistor shorting contact effective to by-p-ass said resistor when said shorting rod conductors are in engagement with the exposed ends of said central conductors in said jack barrels, but inefiective when either shorting rod conductor is disengaged from its respective central conductor (h) and contact means operable to electrically connect a disengaged shorting rod conductor to said jack barrels.

References Cited UNITED STATES PATENTS 5/ 1962 Kienlen et al. ZOO-51.1 11/ 196 3 Giger et al. 333-8 

1. A SELF-NORMALLING JACK FOR SELECTIVELY CONNECTING A FIRST COAXIAL CABLE TO A SECOND, OR FOR DISCONNECTING THEM, AND ALSO ADAPTED TO CONNECT EITHER OF THEM TO OTHER COAXIAL CABLES WHEN DISCONNECTED FROM EACH OTHER, COMPRISING, (A) FIRST AND SECOND JACK BARRELS RIGIDLY AND ELECTRICALLY CONNECTED TOGETHER, EACH HAVING ADJACENT ONE END THEREOF A CENTRAL CONDUCTOR INSULATED FROM THE BARREL, BUT WITH EXPOSED UNINSULATED PORTIONS WITHIN THE BARREL, THE OTHER ENDS OF SAID JACK BARRELS BEING OPEN AND THE WALL OF EACH JACK BARREL HAVING A TRANSVERSE OPENING THERETHROUGH ALIGNED WITH THE EXPOSED PORTION OF SAID CENTRAL CONDUCTORS, (B) A SHORTING ROD EXTENDING TRANSVERSELY OF SAID JACK BARRELS, INTO SAID TRANSVERSE OPENINGS THERETHROUGH AND WITH ITS OPPOSITE ENDS ENGAGING THE EXPOSED PORTIONS OF SAID CENTRAL CONDUCTORS, THEREBY CONNECTING THEM, (C) RESILIENT MEANS URGING SAID SHORTING ROD INTO ENGAGEMENT WITH SAID CENTRAL CONDUCTORS, (D) NON-CONDUCTIVE MEANS EXTENDING INTO SAID TRANSVERSE OPENING IN SAID JACK BARRELS AND INTO THE PATH OF A PATCHCORD OR DUMMY PLUG INSERTED INTO THE OPEN END OF EITHER BARREL, (E) SAID NON-CONDUCTIVE MEANS EACH BEING EFFECTIVE TO SEPARATE ONE END OF SAID SHORTING ROD FROM ITS RESPECTIVE CENTRAL CONDUCTOR UPON THE INSERTION OF A PATCHCORD OR DUMMY PLUG INTO THE OPEN END OF ITS RESPECTIVE JACK BARREL, (F) A NORMALLY ELECTRICALLY FLOATING CIRCUIT IMPEDANCE BALANCING ELEMENT, (G) AND MEANS OPERATIVE TO ELECTRICALLY CONNECT SAID CIRCUIT IMPEDANCE BALANCING ELEMENT TO SAID SHORTING ROD AND TO SAID JACK BARRELS UPON SEPARATION OF EITHER END OF SAID SHORTING ROD FROM ITS RESPECTIVE CENTRAL CONDUCTOR. 